This invention relates to a wing mirror for a motor vehicle, and in particular to a structure for supporting cantilever loads applied to the wing mirror.
Modern wing mirrors for motor vehicles are designed so that they pivotally attach to a vehicle mounting bracket. This pivotal attachment is normally via a vertical spigot on the mounting bracket. The mounting bracket has a base surface surrounding the spigot which supports the mirror head and various detents used to hold the mirror head in the required position. The mirror head is provided with necessary bearing surfaces to enable it to rotate with respect to the spigot. A coil spring is normally used to hold the mirror head against the base surface and any detents that may be located between the mirror head and base surface. The coil spring acts between the mirror head and a retainer that is normally fitted to the end of the spigot.
Such arrangements enable the mirror head to be moved to a park position or enable it to break away upon impact forces being applied.
In addition to manual movement of mirror heads, it has become common to provide electric drive means to automatically move the mirror from a deployed or operating position to a park position where the mirror is moved alongside the vehicle. Again, these mechanisms normally rely on a spigot secured to a mounting bracket about which the mirror head rotates.
A design requirement for wing mirrors is to be able to withstand cantilever loads which are applied at the outermost point of the mirror head. Vehicle manufacturers normally specify the static load which a mirror head must be able to withstand.
This cantilever load results in the mirror head tending to rotate about a horizontal axis. The centre of rotation will normally be the outer edge of the base surface of the mounting bracket which in turn will result in some compression of any coil spring. In turn, the mirror housing will come into contact with the spigot and apply a side loading. This side loading causes a bending strain within the spigot.
Alternatively, if the mirror has an electric drive means, the side loading force may be applied to the drive mechanism.
In most mirror designs, materials are selected to produce cost effective volume manufacture. The most suitable materials are normally polymeric or diecast metals. However, such materials generally have inadequate strength particularly in respect of bending or tensile loads. Accordingly, it has not been though possible to produce suitable and economic designs using these materials which can support significant cantilever loads.
Accordingly, it is an aim of this invention to produce a design which better resists the cantilever forces and to produce a design which is able to withstand higher forces using conventional materials.
In its broadest form, the invention is a wing mirror comprising:
A mirror head,
A vehicle mounting bracket,
A pivot assembly between said mirror head and said mounting bracket enabling the mirror head to pivotally rotate with respect to said mounting bracket, and;
Load support structure comprising a first surface on said mirror head and a second surface fixed with respect to said mounting bracket located over said first surface so that rotation of said mirror head about a horizontal axis is resisted by engagement of said first and second surfaces.
Preferably, the first surface is the upper surface of a flange on the mirror head and the second surface is the lower surface of a ledge fixed to the mounting bracket. The ledge on the mounting bracket is preferably supported some distance above the base surface of the mounting bracket. Other variations will be possible such as the first surface on the mirror head comprising one of the surfaces of a recess within the mirror head.
Preferably there is some clearance between the first and second surfaces to enable the mirror head to rotate freely. However, the clearance should be such that rotation of the mirror head about a horizontal axis does not allow significant side loading to be applied to the pivot means.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.